水平梯度表面能材料表面上的滴状凝结换热系数

本文在均质表面的单个球缺形液滴换热模型和液滴通用尺度分布规律的基础上,结合梯度表面能材料表面的液滴分布和凝结换热特性,得到了一维水平梯度表面能材料表面上的滴状凝结换热计算式。在此基础上,研究了壁面过冷度、接触角梯度、工质物性等参数对梯度表面能材料表面滴状凝结换热性能的影响。结果表明:随着过冷度的增加和凝结工质汽化潜热的增大和表面张力的减小和接触角梯度的增大,平均表面凝结换热系数会增大。

DROPWISE CONDENSATION HEAT TRANSFER COEFFICIENT ON THE HORIZONTAL SURFACE WITH GRADIENT SURFACE ENERGY

A theoretical model was developed for the dropwise condensation heat transfer performance on the horizontal surface with gradient surface energy based on the heat transfer model of individual condensate drop and the size distribution model of condensate drops. The effect of contact angle gradient on the gradient surface on the condensation heat transfer and the drop size distribution was taken account of in this model. The theoretical calculation method was obtained to predict the dropwise condensation heat transfer coefficient on the horizontal surface with gradient surface energy. The effects of wall subcooled temperature, surface energy gradient, and thermophysical properties of condensate on the condensation heat transfer were discussed respectively. The calculation results show that the condensation heat transfer coefficient increases slightly with the increase of wall subcooled temperature. As latent heat increasing and surface tension reducing, the condensation heat transfer coefficient increases. A larger surface energy gradient induces a larger condensation heat transfer coefficient.